© 1991 by London Mathematical Society
Elliptic Hopf Algebras
Institut de Mathématiques, Université Catholique de Louvain B1348 Louvain-la-Neuve, Belgium
Physical Sciences Divisio, Scarborough College, University of Toronto Scarborough, Canada M1C 1A4
U.F.R. de Mathématiques, Université de Lille Flandres, Artois, 59655 Villeneuve d'Ascq, France
An elliptic Hopf algebra is a connected graded cocommutative Hopf algebra that is finitely generated and nilpotent. If (A, m, k) is a local noetherian ring then ExtA(k; k) is elliptic if and only if A is a complete intersection. Similarly, special conditions are imposed on a simply connected topological space X if H*(
X; k) is elliptic.
Elliptic Hopf algebras G have finite depth and we show that they are characterized among Hopf algebras of finite depth by any of the following three properties: (i)
i
n dim Gi grows at most polynomially in n; (ii) G is left noetherian; (iii) G is nilpotent.